Heat hardening in a tropical lizard: geographic variation explained by the predictability and variance in environmental temperatures

Phillips, Ben L., Muñoz, Martha M., Hatcher, Amberlee, Macdonald, Stewart L., Llewelyn, John, Lucy, Vanessa, and Moritz, Craig (2016) Heat hardening in a tropical lizard: geographic variation explained by the predictability and variance in environmental temperatures. Functional Ecology, 30 (7). pp. 1161-1168.

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Over the coming decades, our planet will experience a dramatic increase in average temperatures and an increase in the variance around those temperatures leading to more frequent and harsher heat waves. These changes will impact most species and impose strong selection on physiological traits. Rapid acclimation is the most direct way for organisms to respond to such extreme events, but we currently have little understanding of how the capacity to mount such plastic responses evolves. Accordingly, there is some urgency to determine how the physiological response to high temperatures varies within species, and how this variation is driven by the environment. Here, we investigate heat-hardening capacity - a rapid physiological response that confers a survival advantage under extreme thermal stress - across 13 populations of a rain forest lizard, Lampropholis coggeri, from the tropics of north-eastern Australia. Our results reveal that heat hardening is constrained in these lizards by a hard upper thermal limit for locomotor function (approximately 43 degrees C). Further, hardening response shows strong geographic variation associated with thermal environment: lizards from more predictable and more seasonal thermal environments exhibited greater hardening compared with those from more stochastic and less seasonal habitats. This finding - that predictability in thermal variation influences hardening capacity - aligns closely with theoretical expectations. Our results suggest that tropical species may harbour adaptive variation in physiological plasticity that they can draw from in response to climate change, and this variation is spatially structured in locally adapted populations. Our results also suggest that, by using climatic data, we can predict which populations contain particular adaptive variants; information critical to assisted gene flow strategies.

Item ID: 45540
Item Type: Article (Research - C1)
ISSN: 1365-2435
Keywords: heat shock, local adaptation, plasticity, thermal limits
Funders: Australian Research Council (ARC), CSIRO/JCU Tropical Landscape Joint Venture
Projects and Grants: ARC DP1094646, ARC DP130100318, ARC FL110100104
Date Deposited: 24 Aug 2016 10:53
FoR Codes: 31 BIOLOGICAL SCIENCES > 3104 Evolutionary biology > 310406 Evolutionary impacts of climate change @ 100%
SEO Codes: 96 ENVIRONMENT > 9603 Climate and Climate Change > 960301 Climate Change Adaptation Measures @ 100%
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